Matrix keyboarding system

ABSTRACT

A mobile computing device includes a processor and a touch-sensitive display cooperable with the processor. The processor executes instructions to display a character set on the touch-sensitive display for receiving input from a user of the mobile computing device. The character set includes a plurality of keys that are arranged in an arc. The processor receives the input from the user of the mobile computing device by way of the touch-sensitive display.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/537,282 filed Nov. 10, 2014, pending, which is a continuation-in-part(CIP) of U.S. patent application Ser. No. 13/040,083 filed Mar. 3, 2011,now U.S. Pat. No. 8,884,790, which claims the benefit of U.S.Provisional Patent Application No. 61/310,110, filed Mar. 3, 2010, theentire contents of each of which are hereby incorporated by reference inthis application.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

(NOT APPLICABLE)

BACKGROUND OF THE INVENTION

This invention pertains generally to electronic data entry devices and,more specifically to keyboard data entry devices. The invention pertainsto a new kind of alphanumeric keyboard and a novel system for manuallyinputting alphanumeric information into data processing equipment suchas computers, PDA's, cell phones, and other devices, which, in someembodiments, may send and receive text messages.

As computers continue to evolve into ever-smaller devices such as PDA's,advanced mobile phones, and tablet computers, users still findthemselves bound to unwieldy keyboards for data entry. Users generallyeither have to choose between full-sized keyboards, which negate themain purpose for having a small computer, or they must settle for tiny,hard to use, inefficient keyboards. Until now, there have been severalattempts at making smaller sized, efficient data entry devices, but eachhave had their own limitations.

For decades, the holy grail of data input was considered to be speechrecognition, but even with speech recognition technology maturing, therestill remain a host of issues that render it less than ideal for mostapplications. Many attempts have been made to develop effectivealternative input devices. These approaches have included gloves thatincorporate touch sensors, keyboards that split apart, touch screens,and even virtual keyboards, projected by laser. Attempts at producingone and two-handed combinational keyboards have also been made. Untilnow, none of these approaches has proven effective or practical.

The advent of portable, touch screen tablet computers and other mobilecomputer devices makes possible a new class of ergonomic keyboarddesigns that can exploit a new system of data entry called MATS (MatrixTyping System).

BRIEF SUMMARY OF THE INVENTION

This invention allows data entry keys to be placed in an ergonomicmanner so that when the computer device is being held like a book, theuser's fingertips will naturally rest on the appropriate keys. The useris thus able to “type” or efficiently input keyboard data without movingtheir hands from a natural, comfortable position. Because the fingerscontinually rest upon the keys, it is also possible, with the help of anactuator, to provide key data back to the fingers.

This invention provides a novel and efficient method of manual datainput (also referred to as typing), by exploiting the attributes ofmodern handheld computer devices, including those devices that aretablet styled. This invention further provides a number of uniqueproducts that take advantage of this new method of data input.

In an exemplary embodiment, a mobile computing device includes aprocessor and a touch-sensitive display cooperable with the processor.The processor executes instructions to perform acts including displayinga character set on the touch-sensitive display for receiving input froma user of the mobile computing device, the character set including aplurality of keys that are arranged in an arc; and receiving the inputfrom the user of the mobile computing device by way of thetouch-sensitive display. The step of displaying the character set may bepracticed by displaying plural rows of keys arranged concentrically inthe arc.

In another exemplary embodiment, a method includes the steps ofdetecting a touch by a user on a touch-sensitive display of a mobiledevice; and responsive to the detecting, displaying a character set onthe touch-sensitive display for receiving input from the user, thecharacter set including a set of keys arranged in a plurality of rows,wherein respective ones of the plurality of rows are arranged radiallyfrom a corner area of the touch-sensitive display.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other aspects and advantages of the invention will bedescribed with reference to the accompanying drawings, in which:

FIG. 1 shows the basic matrix typing system (MATS) layout;

FIG. 2 shows the basic character matrix with a possible keypadembodiment;

FIG. 3 shows an alternative character matrix including a shift key;

FIG. 4 shows an enhanced character matrix with multiple shift keys;

FIG. 5 shows key mappings for a number mode;

FIGS. 6-9 show exemplary single hand chords;

FIGS. 10-13 show exemplary mode change command chords;

FIGS. 14 and 15 show an application of how the alphabet may be inpututilizing a 5-position joystick or other 5-position keysets;

FIG. 16 illustrates MATS typing on a touch-screen;

FIG. 17 shows an embodiment with keypads separated from the charactermatrix;

FIG. 18 shows the front of a touch-screen computer with built-in thumbkeys;

FIG. 19 is a rear view of a MATS-enabled tablet style computer;

FIG. 20 shows an arc styled punctuation character set;

FIG. 21 shows a calculator character set;

FIG. 22 shows an embodiment of a clamp-on wireless MATS keypad;

FIGS. 23-25 show an embodiment of handheld MATS;

FIG. 26 shows an embodiment with an accessory device attachable to ahand-held device;

FIG. 27 shows an exemplary keyboard layout of a MATS-enabled device;

FIG. 28 shows usage of a MATS-enabled handheld device;

FIG. 29 shows an embodiment of MATS using finger tip sensors;

FIG. 30 shows an embodiment of MATS integrated into a vehicle steeringwheel;

FIG. 31 shows a safe text communications system;

FIG. 32 shows an application to weapon embedded texting;

FIG. 33 shows a two-way communication scheme for visually or hearingimpaired;

FIG. 34 illustrates a data key with bi-directional capability; and

FIG. 35 shows one of the keyboards including a navigation joystick.

DETAILED DESCRIPTION OF THE INVENTION

With reference to the drawings, the system uniquely exploits thecorrelation between first twenty-five letters of the alphabet placedsequentially within a 5×5 matrix 10, and the five fingers of the leftand right hands. In this system, five keys correspond and are alignedwith each of the five rows of the character matrix 10, and five keyscorrespond and are aligned with each of the five columns. See FIG. 1.With reference to FIG. 2, the data input system preferably includes twokeypads 12 with ten primary keys 14. The keys 14 can be hardware keys,virtual keys, touch-screen emulations of keys, etc. In a preferredarrangement for learning, the keys 14 are configured such that five keysare positioned on one side of the matrix 10 in a manner that each key isassociated and aligned with a specific row of the matrix 10, and acorresponding keypad including the other five keys 14 is placed belowthe matrix 10 so that each key is associated and aligned with a specificcolumn in the matrix 10. The five fingers of both the operator's handsare placed on the keys 14 of each of the respective keypads 12. Theoperator can select characters from the character matrix 10 bysimultaneously pressing the appropriate column key with a finger of onehand and the appropriate row key with a finger of the other hand.

In a computer implementation, input of the character matrix is effectedvia keypads 12 including individual buttons/switches 14 for each fingerof each hand. The communication and cooperable operation between thekeypads 12 and the computer system may be any suitable constructionsimilar to known user interface configurations for existing systems. Thedetails thereof will thus not be further described.

With reference to FIGS. 3 and 4, in addition to the buttons 14 on eachkeypad 12, the keypads may additionally include one or more shift keys16 to effect entry of alternative characters including, for example,lower case letters, numbers, symbols, etc.

Of course, the character matrix 10 may be expanded by adding additionalrows and columns. In this context, each keypad 12 may includecorresponding additional keys 14 for each of the additional rows andcolumns. The additional keys 14 are preferably positioned within reachof a hand “resting” position in which the user's five fingers of eachhand are positioned on five corresponding “home” keys 14. Additionallyor alternatively, each cell within the matrix may contain more than onecharacter. Alternate characters may be selected via alternate keys orshift keys 16 located in the vicinity of each of the primary column androw keys 14. The shift keys 16 may be used to access a full alternatecharacter set via a shift option or the like, activated by a single keyor by other means such as a combination of keys. When an alternatematrix of characters is selected via the shift key 16 or the like, acorresponding change will occur on the display. Additionally, an audiblealert may be issued to note the change.

As an alternative to the shift key 16 for accessing alternativecharacters, other means for accessing alternative characters may includethe force or speed of a key strike. For example, a harder/faster keystrike may cause a normally lower-case character to become capitalized.Alternatively, a harder/faster key strike could cause some otherpredetermined action to take place.

The keyboard data input system may be further configured to beresponsive to “gestures” or chords, where the simultaneous touching oftwo or more keys on the same keypad (as opposed to simultaneous touchingof keys on opposing keypads) can create a new action, a new mode, a newcharacter matrix, etc. For example, the simultaneous key strike by theindex and middle finger on one keypad may select a period, whereas thesimultaneous key strike by those same fingers on the opposite keypad mayact as a “space bar” command. Gestures may also include simultaneoustouching of multiple keys on both keypads. Likewise, special presetcharacters may be assigned to individual keys so that simply “typing”that key will yield the desired character.

In a preferred arrangement, the system is capable of utilizing variouschords or gestures to effect predefined output. It has been discoveredthat utilizing two-finger chords are most effective. It is easier for anew user to understand and implement two-finger chords than more complexchords. From a technical standpoint, working with anything beyondtwo-finger chords may be problematic, because the processor interpretingkeystrokes has no way of knowing whether the user intends to do atwo-finger chord, or if it should wait around for an additionalkeystroke to occur for a more complex chord. Two simultaneouskeystrokes, however, are easy to interpret. When a single key isdepressed, the processor simply waits for the next key to be struck.

Multi-finger gestures (i.e., beyond two-finger chords) may also beviable in limited combinations. For example, in certain cases,multi-finger gestures (e.g., simultaneously holding down the threemiddle fingers on both hands) may place the keyboard into a new mode,such as the “number mode.”

The chords may also enable texting without the use of the auxiliarythumb keys. Apart from the twenty-five characters available on a simple5×5 matrix, there are ten additional characters available withtwo-finger combinations within each hand, for a total of 45 characterspossible with two-finger gestures on 10 keys. This of course isexpandable if a new matrix or mode is called up, via gestures or thelike designed to go into such a mode. For instance, simultaneousselection of four fingers on the left hand may hypothetically be used tocall up a whole new character matrix. For example, with reference toFIG. 5, a number mode may be entered for single finger entry. In thetablet embodiment (discussed with reference to FIGS. 18 and 19 below),the mode may be activated by the simultaneous selection of the twobottom auxiliary thumb keys 22, or by some other prescribed gesture. Asimilar chord may be used for a PDA or smartphone version. When in thenumber mode, each finger will represent a specific number as shown.Depressing a shift key will allow indicated mathematical symbols to beaccessed. Alternatively, while in the number mode, mathematical symbolsmay also be selected by prescribed two-finger chords.

FIGS. 6-9 show exemplary chord mappings for two- and multi-fingerchords. These key mappings (including the matrix) can work regardless ofthe device. The device may be in the form of a single plane (flat)keyboard, or on a tablet where the fingers are under the tablet and thethumbs are on top, or on a steering wheel as it is normally held whiledriving, or even on a weapon with one hand near the trigger, and thehand other on the forestock. It should be easily understood that theability to place keys on any hand-held device so that the keys areeasily accessible to the fingers creates a host of potentialapplications including gaming controllers, vending machines, ATMs, etc.Other applications may be contemplated, and the invention is not meantto be limited to the described exemplary applications.

The mappings essentially provide full keyboard functionality for deviceswith only ten keys (many smaller devices may not necessarily have thereal estate to offer room beyond that number). Those of ordinary skillin the art will recognize that these mappings are given merely asexamples. Other mappings may generate alternative outputs, such asemoticons, complete phrases, and the like, or computer actions, such as“sending” a text message (for example, sending a text message mayrequire the simultaneous holding down the ring finger and index fingerof both hands for one second, which would help to prevent accidentalsending) or mode changes (see FIGS. 10-13). Just as there could bealternate matrices, there could be multiple mappings of the same handchords.

Table 1 below is a summary of the exemplary mappings:

Left Hand Characters Finger Formula Right Hand Characters CAPS Thumb +Index Period Back Space Index + Middle Space Quotation mark Middle +Ring Apostrophe Colon Ring + Pinkie “Z” Comma Thumb + Middle Questionmark Semi-colon Thumb + Ring Exclamation point Open parenthesis (Thumb + Pinkie Close parenthesis ) Dash (minus sign) − Index + Ring Plussign + Slash (division sign) / Index + Pinkie Asterisk (multiplicationsign) * Ampersand “&” Middle + Pinkie @

With reference to FIGS. 14 and 15, if the user is working with a screen,then a small 5-position thumb controlled joystick 17 could be utilizedfor one of the thumb keys. Cursor control is via the four buttons on theperiphery: left, right, up, down. The middle section could operate as anormal or enter button. Fingers are positioned over keys so typing canoccur with just one hand. Alternately, a single five-position left handkey could be used in combination with a single five-position right handkey, so that the left hand key selects one of five character maps, andthe right hand key selects the position on the character map to beinput. Just two thumbs (or fingers) would provide convenient access totwenty-five letters of the alphabet, with applications in gaming andtexting. An accessory key of the same type can greatly expand theutility (fill in the missing links: punctuation, etc.). A relatedjoystick 117 may comprise an added input key, in addition to thestandard ten keys. See FIG. 35. The joystick 117 may be used fornavigation.

In the context of the matrix application using separate keypads 12 andkeys 14 for each finger, the interface can come in any form orconstruction, including, for example, traditional hardware style dataentry keys, the touch-screen for data entry, a projected keyboard orother virtual keyboard for receiving keystroke data, a motion sensorthat can detect the finger motion as a “virtual” key press, etc. and/orcombinations thereof.

As shown in FIG. 16, in an exemplary application for a touch screen, thecharacter matrix 10 may be displayed with the corresponding keypad tofacilitate learning of the matrix data entry system. In one embodiment,when used with a display 15, the selection of the key corresponding tothe desired row or column causes the full column or row to be visuallyhighlighted. The particular “cell” defined by the inner section of theselected row and column is also caused to be specially illuminated orvisually differentiated from the remainder of the characters. In atablet computer or the like, the touch-screen system can become a “touchtyping” training tool for learning the character matrix. The user isable to type directly onto the display screen, and once having learnedthe matrix, the user is instinctively able to operate more efficienthardware versions of the keypad, including those that may be builtdirectly into the host device, attached to the host device or mayoperate independent of the host device. In some arrangements, thecharacter matrix 10 can be removed from the keypads to effect a morecompact keyboard system. See FIG. 17.

FIGS. 18 and 19 show an exemplary tablet style computer 18 with thematrix keypads 12 integrated into the hardware. In this context, thekeypads and components are physically attached to the host systemcomponents, such as the CPU and the display, so the system is able toreceive power from the host system and communicate directly with thehost system. Alternatively, the keypads and components may be locatedremotely from the other system components, where power and datacommunications with the host device may be provided via wired orwireless connections. In still another alternative, the keypad system isbuilt as a separate unit that may clip on, slip on as a case, orotherwise attach to and communicate with a device such as an advancedphone, tablet computer, PDA, ebook or other communication device orcomputer (discussed in more detail below with reference to FIG. 22). Thekeypads 12 may take the form of an egg, a sphere, a bar or any otherobject that would be comfortable to hold by hand and be a suitableplatform for mounting of appropriate keys.

The front of the tablet computer 18 is shown in FIG. 18, and the back ofthe computer 18 is shown in FIG. 19. The keyboard input system includesa plurality of keys 14 for the user's fingers on the backside of thecomputer 18. A touch pad 20 may also be provided for cursor control. Onthe front side of the computer 18, one or more thumb keys 22 areprovided. As shown, three thumb keys 22 may be provided for each of auser's thumbs in order to add increased functionality. With the tabletcomputer 18 held in the hands as a book or a pad would be held, the datainput keys 14, 22 and touch pad 20 are located in a position convenientto the normal placement of the fingers, typically with thumbs on the topside and the remainder of fingers underneath. The keys 14 may berecessed ergonomically into the body of the device 18, positionedconvenient to the normal placement of the fingertips. The touch pad 20can be easily accessed by one or more of the user's fingers whileholding the device 18 in a normal manner.

As an alternative to the use of keys 14, 22, a sensor sensingcapacitance or the like may sense the location and movement of theuser's fingers so that the device can immediately receive input datafrom the fingers regardless of their position. Motion-type sensors mayalso be used. In a similar context, 3M, a company located in St. Paul,Minn., has developed a new, hi-res touch screen film that is flexibleand is multi-touch capable. This film could potentially wrap around tothe back side of a hand held or tablet-style computer. The material cansense up to twenty simultaneous finger inputs. In theory, a user couldsimply hold such a device in their hands, and the finger positions couldbe determined by the device, so that the user could just type using theMATS input methodology without requiring specific positions for theuser's fingers.

The keypads 12 may contain an inertial or other internal referencesystem so that movement of the keypad results in a corresponding “mouse”movement on a display device. The keypads may integrate a mouse orjoystick controller for control of the display and may includeprovisions for “selecting” or “clicking” items in the display. Incertain embodiments, individual keys may also function as a mouse pad orjoystick so that they may control a variety of actions, including, forexample, cursor control.

With reference to FIGS. 20 and 21, the data input system can enablespecial character sets 30 to appear on a hand-held touch-screen display,such as on a tablet computer 18. As shown, the character set 30 ispreferably oriented in a manner to make it easily accessible by theuser's thumb and may be selected by the touch of a thumb or otherfinger. In FIG. 20, the character set 30 is for punctuation and isdisplayed in an arc orientation. Another example is shown in FIG. 21,showing a calculator that is displayed graphically consistent withtraditional calculators and where numbers and functions are selected bytouching the characters with a single thumb or other finger. In asimilar context, the user may be able to customize the selectablecharacters within a matrix, and in the case of a touch-screen system,the user can customize the matrix by dragging and dropping characters,etc. into the matrix. Consistent with the operation of tablet computersand other touch-screen devices, the user can reposition the location ofthe customized character set on the display by dragging or the like.

With reference to FIG. 22, in an alternative embodiment, the keyboarddata input system may take the form of a U-shaped configuration 24, orother suitable shape that can attach to an electronic device such as atablet computer 18. In one construction, each keypad 24 includes atleast five keys 14, with at least one thumb key 26 positioned on oneside of the device (preferably the display side) and four finger keys 28positioned on the opposite side of the device (preferably the backside). The unit 24 can be connected via a USB port or other hardwareconnection or may communicate with the device 18 wirelessly. As analternative to the thumb keys 26, the thumb keys may be replaced bygraphical or virtual buttons on the touch-screen.

With reference to FIGS. 23-25, the keypads 12 may come in the form ofseparate and independent units easily gripped in the user's hands. Eachunit similarly includes keys 14 that are placed for one-handed operationbased on where the user's fingers will fall depending on the shape ofthe units. As shown in FIG. 25, there is a close relationship betweenthe horizontal (flat) matrix and other platforms. Once the matrix datainput concept is mastered, the user may easily transition to deviceswith other form factors and configurations.

FIGS. 26-28 show an application of the keyboard input system to asmartphone, PDA or the like. In the configuration shown, the keyboardinput system takes the form of an accessory 44 attachable to the device46. The accessory include keypads 12 for a user's left and right handsincluding finger buttons 14 and separated thumb buttons 48. With thedevice held in a “landscape” orientation (see FIG. 28), the user'sfingers and thumbs naturally rest on the respective keys of thekeyboards. The accessory 44 communicates with the device 46 by anysuitable means including, for example, a direct wired connection or by awireless connection.

For hardware attachable to existing structure, power for the hardwarecan be provided in any suitable manner. For example, the device may bepowered by rechargeable battery or via a direct connection to the hostdevice with a USB connection or other port. The device can alternativelyor additionally be powered by the electricity generated by the physicalactivity of pressing the keypad, whether by piezoelectric means or anyother means. As still another alternative, power may be provided byinduction from the host device or from an electromagnetic field createdby the host device. Power may also be provided in the form of an RFtransmission.

The device may include an accessory finger guide for small touch-screensthat provides cutouts or indentations that allow the user to easilylocate the proper finger positions. This same guide may function as arestraining device for the fingertips so that they are unable to comeinto contact with the touch-screen until a prescribed amount of pressureis exerted by the fingers, thus preventing premature data input.

With reference to FIG. 29, the key pads may take the form of gloves 38including sensors 40 that enable data input by pressing the sensors 40onto any hard surface. As an alternative to the gloves 38, the datainput device may merely include small sensors that are placed as caps onthe fingertips to effect data input by pressing the sensors 40 onto ahard surface.

FIG. 30 shows an embodiment utilizing a keyboard data input systemintegrated into the steering wheel 42 of a vehicle. The keys or sensorscan be mounted or embedded in the steering wheel 42 for safe texting.With the above-noted 3M material incorporated into a steering wheel, theuser could potentially have his finger positions recognized and would beable to use the steering wheel itself as a keyboard entry device.

The safe texting system may additionally be viable by enabling safetransmission of data without looking down at a device. With reference toFIG. 31, upon data entry via the steering wheel 42, the data isconverted by a component 422 of the system processor into data that iscompatible with a cellular phone or other communications device. Thedata may be converted to speech, and in some variations, may be heard inthe sender's own voice. Incoming text will come into the device, andthen be converted into to speech via a processor component 424, which isthen played audibly, preferably through the automobile's audio system426. The text may be recalled in the user's own voice. This can be donevia software, where a user speaks certain prescribed words, from which aportable voice file (pvf) is then created for each user. That way,texting friends can forward their voice file to each other so that whena text message is received, the smartphone or other device will read itout loud and in their own voice. Other applications of this concept areshown in FIGS. 32 and 33. FIG. 32 shows a weapon embedded texting system500. The weapon is provided keyboard units that can send and receivedata via a processor or the like. FIG. 33 shows a similar text to speechmodule, which also may be configured for hearing impaired via the use ofan actuator key (described below with reference to FIG. 34). Otherapplications may include surveying instrumentation, medical officerecord keeping devices, delivery service provider tablets, vendingmachines, etc.

FIG. 34 shows an exemplary data key with bi-directional capability. Thekey includes a key cap 34 and an actuator 36. The key 32 is capable ofboth sending data information (as a normal keyboard key) and also by theactuator 36 to produce movement in the key cap 34, which the user candiscern and interpret as character information. The key cap allows theuser to “feel” incoming data through the user's fingers. This systemmakes possible two-way texting, which would be especially useful for thevisually impaired.

The corresponding relationship of the fingers with the alphabeticalmatrix is the basis for the MATS keyboard system, and makes possible avariety of new products that can take advantage of the MATS system.

The advantages of the MATS system are many:

-   -   Keyboards can be infinitely portable    -   Keyboards can offer traditional keyboard tactile feel    -   Keyboards can be easily mastered, even by children    -   Rapid “typing” is possible due to fact that fingers remain over        home keys    -   Inexpensive to implement    -   Works with real or virtual keys    -   Wired or wireless embodiments    -   Makes possible “safe” texting devices that can be used while        driving    -   Built-in key actuators, make possible 2-way communication        through the fingers.

The advent of portable touch-screen computers creates a perfect platformfor the MATS system. The touch screen makes possible on-screen learningand training programs where the user can create customized charactermatrices and virtual keyboards. The ability of the row and column to begraphically highlighted with each keystroke helps make learning thematrix fun and easy. The touch-screen also provides a great platform forthe creation of learning games, which can help improve MATS proficiency.

Once the touch-screen character matrix is learned, the user can thenquickly transition to more advanced, “real key” MATS keypads that can bebuilt into the user's device or may be mounted as an accessory. The MATSkeypads can be built ergonomically, so that it conforms to the naturalcontours of the user's hands, positioning the user's fingers directlyover their respective keys. Optional wireless functionality allows thekeypad to seamlessly communicate with the host device.

One of the major benefits from the MATS system is its ability to providefull keyboard functionality in a very compact size. In fact, MATSsystems can even be built into gloves, steering wheels, or small devicesthat may be held in the palm of one's hands.

One application for MATS is as an accessory that may attach, or be builtinto a touch screen phone, or other small communications device. Also,because the MATS system allows the user's fingers to remain over the“home” keys, it is possible, with appropriate actuators, to send databack to the user, by moving or vibrating their fingers, so that the usercan “hear” text or other information through their fingers.

While the invention has been described in connection with what ispresently considered to be the most practical and preferred embodiments,it is to be understood that the invention is not to be limited to thedisclosed embodiments, but on the contrary, is intended to cover variousmodifications and equivalent arrangements included within the spirit andscope of the appended claims.

1. A mobile computing device comprising a processor and atouch-sensitive display cooperable with the processor, wherein theprocessor executes instructions to perform acts comprising: displaying acharacter set on the touch-sensitive display for receiving input from auser of the mobile computing device, the character set including aplurality of keys that are arranged in an arc; and receiving the inputfrom the user of the mobile computing device by way of thetouch-sensitive display.
 2. A mobile computing device according to claim1, wherein the step of displaying the character set is practiced bydisplaying plural rows of keys arranged concentrically in the arc.
 3. Amethod comprising: detecting a touch by a user on a touch-sensitivedisplay of a mobile device; and responsive to the detecting, displayinga character set on the touch-sensitive display for receiving input fromthe user, the character set including a set of keys arranged in aplurality of rows, wherein respective ones of the plurality of rows arearranged radially from a corner area of the touch-sensitive display.